"We are the only country in history that ever deliberately changed its ethnic makeup, and history has few examples of 'diversity' creating a stable society." - Richard Lamm, former governor of Colorado

Tuesday, July 17, 2007

The average IQ of immigrants’ country of origin predicts a lot about immigrants’ earnings in the United States

Thirteen years after Herrnstein and Murray’s The Bell Curve outraged the country, it’s hard to find a serious social scientist who denies that intelligence is a Very Big Deal. But it still takes courage to push the envelope. That’s just one of the reasons why I’m thrilled that Garett Jones, a leading expert on economics and IQ, will be joining the faculty of George Mason University, where I work, this fall.

So what’s Garett been up to? For starters, he’s done the most careful statistical study (with co-author W. Joel Schneider) of the relationship between intelligence and economic growth. Published in the prestigious Journal of Economic Growth, the Jones-Schneider study find that “In growth regressions that include only robust control variables, IQ is statistically significant in 99.8% of these 1330 regressions, and the IQ coefficient is always positive. A strong relationship persists even when OECD countries are excluded from the sample. A 1 point increase in a nation’s average IQ is associated with a persistent 0.11% annual increase in GDP per capita.”

Garett’s got another neat paper on intelligence and cooperation in Prisoners’ Dilemma experiments. By combining data from many previous experiments, and looking up the average SAT scores of the schools where the experiments were conducted, Garett answers a big question on the cheap. Result: “A meta-study of repeated prisoner’s dilemma experiments run at numerous universities suggests that students cooperate 5% more often for every 100 point increase in the school’s average SAT score.”

But my personal favorite is Garett’s job market paper (also co-authored with Schneider), “IQ in the Production Function: Evidence from Immigrant Earnings.” A common objection to international IQ comparisons is that the tests are not cross-culturally valid. This paper shows that the average IQ of immigrants’ country of origin predicts a lot about immigrants’ earnings in the U.S. In short, despite obvious shortcomings of international IQ tests, they still predict real-world outcomes right here in the U.S.